Various medical devices can non-invasively measure physiological parameters of a patient. Some of these devices include pulse oximetry devices and electroencephalogram (EEG) measurement devices, among others. An example is the BIS™ brain monitoring system from Covidien LP (Boulder, Colo.). These devices can measure pulse, breathing rates, brain activity, or other parameters experienced by the patient during various medical procedures, such as surgery and subsequent recovery.
Patient pain levels during sedation can be difficult to quantify and measure due to the subjective nature of pain, as well as due to a consciousness level of the patient. In some medical procedures the patient receives anesthesia or other conscious pain reduction treatments, which can include unconsciousness, amnesia, analgesia, and muscle relaxation, which make quantification and measurement of pain levels difficult. Furthermore, patient-to-patient variation in pain response and the possibility of subjectivity in nociception pain response measurements make pain response measurements difficult.
Some physiological measurement techniques, such as EEG measurements, can provide an indication of a current level of brain activity, and corresponding depth of anesthesia, experienced by a patient, but do not identify a pain response of that patient. Capacitive sensing has been employed to measure some physiological parameters by applying electric fields to the tissue of the patient. However, this capacitive sensing merely measures parameters such as pulse rate of a patient for blood perfusion and oxygen saturation measurements.